JP2014177996A - Fastening part structure and processing method for screw hole burring part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable screw fastening to be performed with predetermined fastening torque by applying burring processing to a thin sheet-metal material.SOLUTION: In an approximately cylindrical burring part 11, a burring-processed fastening material 1 is folded in a circumferential direction, and corrugated burring 11 elongated along a longitudinal direction of a cylindrical shape is applied.

Description

  The present invention relates to a screw fastening portion structure of a screw hole for fastening a screw to a metal sheet metal and a screw hole burring method. In particular, the present invention relates to a fastening portion structure of a thin metal material that performs burring processing around a screw hole and reinforces screw fastening, and a processing method of a screw hole burring portion in the fastening portion structure.

  2. Description of the Related Art Conventionally, a structure in which a plate material that is a fastening material formed of a metal material and a material to be fastened made of a metal plate material or a resin material similar to the fastening material are fixed with screws. Fixing with screws is easy to install and remove in the production of devices and parts replacement in the market, etc., so it is often used. In a fastening material having a certain degree of thickness and a material to be fastened, the fastening material and the material to be fastened are fixed by engaging a screw with a screw hole that engages with a screw provided on the fastening material and the material to be fastened.

  On the other hand, even when the thickness of a plate material such as a metal plate, which is a fastening material, is as thin as about 1 mm, it is necessary to securely fix the material to be fastened to the fastening material with a thin plate screw. For this purpose, burring processing is performed on the screw hole portion of the fastening material that engages with the screw, and the screw hole body portion height (hereinafter referred to as “burring height”) that is the screw engaging portion is secured. There is known a method of increasing the screw engaging portion by the burring process rather than the thickness when the screw thread of the screw and the screw hole of the fastening material are simply machined into the fastening material.

  In Patent Document 1, the inner peripheral surface in the vicinity of the foremost portion of the tap pilot hole that forms a screw by plastic deformation is inflated inward to form a thickened portion, and the inner diameter of the thickened portion is set under the tap. There has been proposed a tapped pilot hole burring structure characterized by a smaller diameter than the inner diameter of the hole.

  By adopting such a technical configuration, the catch rate of the effective thread is set to 100%, the tightening torque is increased, and the strength of the fastening portion is increased as compared with the conventional method.

  In order to reduce the processing cost and the processing man-hour in the burring processing performed on the fastening material and to improve the efficiency, the following method is used as a solution in order to increase the processing man-hour when performing the burring process as described above. Has been proposed.

  This is a draw-out burring method with a pre-drawer having a pre-drawer formed by a single step of burring forming other than the small-diameter piercing burring, such as a screw pilot hole, which has been conventionally performed in two steps. That is, Patent Document 2 shows a burring method characterized by performing processing using a squeezing burring punch shape with preliminary squeezing and squeezing with preliminary squeezing in the squeezing burring process with preliminary squeezing. .

  Furthermore, Patent Document 3 does not provide a structure that eliminates the need for a so-called work pressing mechanism such as a pad or a stripper, while assuming that the embossed portion is formed and pierced holes are formed in one step. In other words, in cooperation with the lower die having the button die in which the die hole is formed and the upper die having the piercing punch, the molding of the embossed part on the panel and the processing of the pierced hole in the corresponding part of the embossed part are performed in one step. To do. At that time, the pierced hole is processed in advance by the shearing action of the pierce punch and the die hole based on the lowering movement of the upper mold, and the lower and upper molds are embossed later than the pierced hole. It is known that the embossed part is formed by pressurizing and restraining the periphery of the pierced hole between the molding surfaces.

Japanese Utility Model Publication No. 6-66821 Japanese Patent Laid-Open No. 09-164431 JP 2009-214151 A

  Here, in Patent Document 1, a burring process is provided in which the inner peripheral surface in the vicinity of the most distal end portion of the tap pilot hole is bulged inward to form a screw fastening portion increasing shape. The inner diameter of the burring is a tap pilot hole diameter, and the material to be fastened can be fastened with a metric coarse screw or a self-tapping screw.

  Further, the purpose of performing the burring process is to provide as many screw thread contact portions as possible in order to secure the screw fastening force. For this purpose, it is necessary to increase the burring height, and thus the thickness formed by the burring inner diameter portion and the burring outer shape portion must be reduced, but this thickness is not destroyed by the penetration of the screw. It is set on the assumption.

  However, as the plate thickness of the fastening material decreases, the wall thickness formed by the burring inner diameter portion and the burring outer shape portion cannot be sufficiently secured, and the thin wall portion is broken by the screw, generating sufficient fastening force. There is a possibility that it will not be possible. However, when burring is performed, an R-shaped relief shape is generated at the base of the narrowed portion. For this reason, when using a stepped screw, the seat surface which receives the level | step difference of a stepped screw fully may not be ensured. Therefore, when the number of stepped portions is increased, there is a problem that the entire screw portion becomes large and the entire device becomes large due to the influence.

  Moreover, in patent document 2, although it is excellent at the point which can carry out a burring process in one process, since the bending circumference part of a burring has R shape, a stepped screw is utilized like patent document 1. In such a case, it is necessary to pay attention so that there is a margin in setting the seating surface. In addition, there is a certain relationship between the burring height and the size of the scrap material that has been removed, such that if the burring height is increased, the amount of scrap is reduced. However, in this processing method, if the burring height is increased, there is a risk that cracks may occur in the burring portion.

  Furthermore, since it is impossible to increase the thickness of the burring portion without generating scrap material, there is a problem that there is a limit to applying the thickness of the plate thickness to be applied to a thin plate.

  Furthermore, in patent document 3, it is excellent in the aspect which achieves formation of an embossing and a piercing hole in one process, can tap a piercing hole, and can reinforce it by an embossing part. However, when the plate thickness is thin, from the viewpoint of screw fastening, if a shearing force is applied to the screw portion after screw fastening, the screw to be fastened may be easily collapsed due to deformation of the sheet metal.

  Further, since the amount of the screw is small, the strength is insufficient, and there is a problem that it is easy to break and a necessary fastening torque cannot be obtained.

  Further, when viewed from the plane side, it is circular embossing, and the stepped portion of the embossed edge has a crank-like cross-sectional shape, so that the bending strength is improved. However, the pierced hole at the center has not been reinforced.

  Here, an example of screw fastening to a conventional thin plate subjected to burring processing will be described. 1 and 2 show experimental results showing a state of a fastening portion structure 90 for fastening a screw to a conventional burring shape of a thin sheet metal that is a thin steel sheet. FIGS. 1A, 1B, and 1C are cross-sectional views showing a conventional screw fastening state, and are diagrams showing a state of deformation and destruction of a fastening portion when a screw is fastened. FIG. 2 is a cross-sectional photograph showing a conventional screw fastening strength and a screw fastening torque curve diagram.

  First, the fastening part structure 90 shown to Fig.1 (a)-(c) is demonstrated.

  The screw 3 has a screw head 31 and a screw foot 32 which is a screw part. A cross hole shape (not shown) for rotating the screw 3 with a cross driver or the like is formed on the top 33 of the screw head 31. A male screw 32 a that is a screw thread is formed on the outer peripheral surface of the screw foot 32. The screw head 31 is integrally formed with a screw head portion 34 which is a part of the screw head 31 and is formed in a flange shape which is disposed on the screw foot 32 side and has a large diameter. The screw brim part 34 contacts the material to be fastened 2 at the brim contact part 2a.

  The fastening material 1 which is a metal plate such as a thin steel plate has a burring portion 1 ′ in which a part of the fastening material 1 is squeezed up to a burring height (h) by burring.

  FIG. 2 is a graph and a cross-sectional photograph showing a screwing torque state when a tapping screw 3 is fastened to a fastening material 1 which is a thin steel plate subjected to a conventional burring process.

  According to the leftmost cross-sectional photograph in FIG. 2, the female thread portion is not cut in the burring portion 1 ′ (FIG. 2A: after burring processing) of the fastening material 1. Using this fastening material 1, the fastened material 2 is fastened by tapping screws 3 while female threads are cut in the engaging portion (FIG. 2 (b): 1.3 N · m fastening). As shown in the graph, when the tapping screw 3 is screwed, the screw torque changes. In the fastening part exceeding the breaking torque, the internal thread inside the engaging part is broken (FIG. 2 (c): after breaking).

  Further, as shown in the cross-sectional photograph at the center of FIG. 2 (FIG. 2B: 1.3 N · m fastening), when the tapping screw 3 is fastened to the burring portion 1 ′ of the fastening material 1, A biasing force is applied so that the tip end portion of the portion 1 ′ spreads outward in a funnel shape. The sheet metal as used in this example is particularly weak in tensile strength and easily spreads, so there is a problem that the formation of self-tap is reduced, and the maximum breaking torque is also reduced. At the same time, as shown in the right sectional view of FIG. 2 (FIG. 2 (c): after fracture), the thread of the female thread of the burring portion 1 ′ is scraped off first and breaks. It becomes easy to become.

  As shown in FIG. 1, when using a plate-shaped flanged screw 3 (for example, the product name “RS tight” manufactured by Nitto Seiko Co., Ltd.) that has been devised and marketed to increase the fastening torque, it is fastened outside the throttle part. A force is applied, and the fastening material 1 which is a thin sheet metal is deformed by a screw fastening force. At this time, deformation of the fastening material 1 as shown by the arrow A in FIGS. 1A, 1B, and 1C occurs. In the case of such a fastening part structure 90, there is a problem that the function of preventing deformation of the fastening material 1 and the material to be fastened 2 and obtaining a stable fastening force when refastened cannot be sufficiently satisfied.

  2 is made of SECC-SD material (electrogalvanized steel sheet) having a thickness of 0.6 mm. The fastening material 1 is subjected to burring processing in which a pilot hole with a diameter of 2.78 mm is set for a tapping screw of a metric coarse screw M3. In this example, an aspect in which a product name RS tight (see JP-A-11-247817) and M3 (metric coarse screw) size of Nitto Seiko Co., Ltd. are mounted is shown. In the central cross-sectional photograph of FIG. 2 (FIG. 2 (b): 1.3 N · m fastening), it is fastened with a fastening force of 1.3 N · m that is 70% of the thread breaking torque, which is a normal fastening torque. It is. It can already be seen that the fastening material 1 and the material to be fastened 2 are jack-up deformed by the screw fastening force on the screw head side inside the screw flange portion 34 of the screw 3.

  That is, adopting a screw for obtaining a strong fastening force with a thin sheet metal deforms both the fastening material 1 and the material 2 to be fastened, thereby degrading the planar accuracy. For this reason, there is a problem that it cannot be employed particularly in a place where reassembly and reassembly are performed.

  For the above reasons, after forming the screw part on the inner surface of the burring part, it is possible to use a binding screw or pan head screw that has a flat screw head fastening surface and does not have a countersunk screw shaped screw part. Will weaken and prevent deformation. However, when it is used in a device that is subject to a large thrust load, the screw is likely to loosen in situations such as vibration tests and drop impact tests. As a result, a displacement between the fastening material and the material to be fastened occurs in the thrust direction, and there is a possibility that the performance of the apparatus is upset. In order to prevent this reduction in fastening force and obtain equivalent rigidity, it is necessary to increase the number of screws that are insufficient. For this reason, since many screws are used, there has been a problem that it takes time to assemble, maintain, disassemble and recycle. According to the above conventional example, there are the following problems to be solved in order to fasten the screw with an appropriate fastening force to the fastening material that is a thin sheet metal from the experimental result and the like.

  The burring height (h) needs to be increased in order to provide as many contact engagement points between the thread 32a and the screw holes as possible. However, when the burring height (h) is increased according to the principle of constant volume, the thickness formed by the burring inner diameter portion and the burring outer shape portion is reduced. Accordingly, the fastening force of the screw 3 cannot be secured because the thin portion is broken by the penetration of the thread 32a of the screw 3 into the thin portion of the burring portion 1 '.

  Furthermore, as the plate thickness of the fastening material 1 becomes thinner, the wall thickness of the burring portion 1 ′ formed by the burring inner diameter portion and the burring outer shape portion cannot be sufficiently secured, and the fastening force of the screw 3 decreases. Furthermore, when the screw fastening surface of the fastening material 1 is also a screw having a dish-shaped flange-shaped screw flange portion in which the lower surface of the screw head 31 is inclined from the outer periphery of the screw flange 34 toward the screw foot 32, the jack by the screw fastening force is used. Increases and the fastening surface swells.

  Accordingly, an object of the present invention is to provide a fastening portion structure and a screw hole burring portion machining method capable of performing burring on a thin sheet metal material and screw fastening with a predetermined fastening torque.

  The above object is achieved by the fastening part structure and the method for machining the screw hole burring part in the fastening part structure according to the present invention. According to one aspect of the present invention, a screw having a screw head and a screw portion, a fastening material fastened by the screw, and a fastened to be fastened to the fastening material by being sandwiched between the screw and the fastening material In the fastening portion structure formed by a substantially cylindrical burring portion protruding in a burring screw insertion direction, the screw hole of the fastening material into which the screw is screwed is provided. A cylindrical burring part is provided with a fastening part structure in which the burring-processed fastening material is folded in the circumferential direction and is a wave-shaped burring extending along the cylindrical longitudinal direction. Is done.

  According to another aspect of the present invention, a screw having a screw head and a screw portion, a fastening material fastened by the screw, and a workpiece sandwiched between the screw and the fastening material and fastened to the fastening material. A screw hole in the fastening portion structure formed by a substantially cylindrical burring portion projecting in a burring-processed screw insertion direction. A method for processing a burring part, which is a hemispherical drawing process for the thin plate material constituting the fastening material, followed by drilling, radial bead forming process, and then drawing and increasing the thickness. Then, a processing method of the screw hole burring portion of the fastening portion structure is provided, in which the corrugated burring is formed by performing planarization processing.

  According to the present invention, a thin sheet metal material can be subjected to burring and can be screwed with a predetermined fastening torque.

It is sectional drawing which shows the jack-up state of the fastening material at the time of fastening of the conventional screw fastening part structure. FIG. 1A is a diagram showing that the lower surface of the fastening material and the material to be fastened are deformed by jack-up by the screw fastening force, and FIG. 1B is a diagram showing that the upper surface of the fastening material is deformed. FIG.1 (c) is a figure which showed that the lower surface of a fastening material deform | transforms. It is a cross-sectional photograph which shows the fastening strength of the conventional screw fastening part structure, and a screw fastening torque curve figure. FIG. 2A is a cross-sectional photograph of a conventional fastening material subjected to burring. FIG. 2B is a cross-sectional photograph of a fastening portion structure in which a tapping screw is fastened to a conventional burring processed fastening material and a fastened material. FIG. 2 (c) is a cross-sectional photograph after a conventional burring processed fastening material and a material to be fastened are fastened with a tapping screw and broken. FIG.2 (d) is a graph about the screwing time and screw torque of a tapping screw in the conventional fastening part structure. It is a figure of the screw fastening part structure of one Example of the fastening part structure which concerns on this invention. 3A is a schematic side view of the screw fastening portion structure, FIG. 3B is a schematic plan view of the screw fastening portion structure viewed from the screw head direction, and FIG. 3C is a schematic cross-sectional view of the screw fastening portion structure. It is. It is a figure of the screw fastening part structure to which the example of the fastening part structure concerning the present invention is applied. FIG. 4A is a front perspective view of the screw fastening portion structure viewed from the screw head direction, and FIG. 4B is a back perspective view of the screw fastening portion structure viewed from the screw foot portion direction. It is the figure which gave the burring process to the fastening material of the fastening part structure of Example 1. FIG. FIG. 5A is a schematic side view, FIG. 5B is a plan view of the surface side of the fastening material viewed from the direction opposite to the burring, and FIG. 5C is a schematic cross-sectional view. It is the figure which gave the burring process to the fastening material of the fastening part structure of Example 1. FIG. 6A is a front perspective view of the fastening material, and FIG. 6B is a rear perspective view. It is a figure which shows the press work process which performs a burring process to the fastening material of the fastening part structure of Example 1. FIG. FIG. 7A is a front perspective view, and FIG. 7B is a rear perspective view. FIGS. 7C to 7E are schematic cross-sectional views showing examples of other shapes of corrugated burring. It is a figure which shows the press work process which performs a burring process to the fastening material of the fastening part structure of Example 1. FIG. 8A is a schematic side view, FIG. 8B is a schematic surface plan view, and FIG. 8C is a schematic cross-sectional view. It is a figure of the fastening part structure of Example 2. FIG. 9A is a schematic side view, FIG. 9B is a surface plan view, and FIG. 9C is a schematic cross-sectional view. It is a figure of the fastening part structure of Example 2. FIG. FIG. 10A is a front perspective view, and FIG. 10B is a rear perspective view. It is a figure which shows the state which fastened the screw | thread to the fastening part structure of Example 2. FIG. FIG. 11A is a front perspective view, and FIG. 11B is a rear perspective view. It is a figure which shows the state which fastened the screw | thread to the fastening part structure of Example 2. FIG. 12A is a schematic side view, FIG. 12B is a surface plan view, and FIG. 12C is a schematic cross-sectional view. It is a figure which shows the press work process of the burring part of Example 2. FIG. 13A is a schematic side view, FIG. 13B is a surface plan view, and FIG. 13C is a schematic cross-sectional view. It is a figure which shows the press work process of the burring part of Example 2. FIG. FIG. 14A is a front perspective view, and FIG. 14B is a rear perspective view. It is a figure of the burring part of the fastening part structure of Example 3. FIG. 15A is a schematic side view, FIG. 15B is a schematic surface plan view, and FIG. 15C is a schematic cross-sectional view. FIG. 16A is a front perspective view and FIG. 16B is a rear perspective view of the burring portion of the fastening portion structure of the third embodiment. It is a figure which shows the press work process of the burring part of the fastening part structure of Example 3. FIG. 17A is a schematic side view, FIG. 17B is a surface plan view, and FIG. 17C is a schematic cross-sectional view. It is a figure which shows the press work process of the burring part of the fastening part structure of Example 3. FIG. 18A is a front perspective view, and FIG. 18B is a rear perspective view. It is a figure of the fastening part structure of Example 4. 19A is a schematic side view, FIG. 19B is a schematic surface plan view, and FIG. 19C is a schematic cross-sectional view. It is a figure which shows the press work process of the burring part of the fastening part structure of Example 4. FIG. 20A is a front perspective view, and FIG. 20B is a rear perspective view. It is a figure of the fastening material of the fastening part structure of Example 4. FIG. FIG. 21A is a schematic side view, FIG. 21B is a schematic surface plan view, and FIG. 21C is a schematic cross-sectional view. It is a figure of the fastening material of the fastening part structure of Example 4. FIG. FIG. 22A is a front perspective view, and FIG. 22B is a rear perspective view.

  Hereinafter, the fastening part structure according to the present invention will be described in more detail with reference to the drawings.

Example 1
3 (a), (b), (c), and FIGS. 4 (a), (b) are views showing an embodiment of a fastening part structure according to the burring process of the present invention.

  As shown in the figure, in the fastening part structure 90 according to the present invention, the fastened material 2 is fastened to the fastening material 1 by being screwed into the fastening material 1 between the screws 3 and the fastening material 1. Yes.

  The screw 3 has a screw head 31 and a screw foot 32. In this embodiment, a screw brim portion 34 having a large diameter is integrally formed on the screw foot 32 side of the screw head 31. The screw rib part 34 forms a part of the screw head 31 and forms a seat surface part 31 a of the screw head 31.

  As shown in FIG. 3B, a cross hole shape 33 a for rotating the screw 3 with a cross driver or the like is formed in the top 33 of the screw head 31 at one end of the screw foot 32 of the screw 3.

  As shown in FIG. 3C, a male screw 32 a that is a screw thread is formed on the outer peripheral surface of the screw foot 32. As described above, the screw flange portion 34 constituting the seat surface portion 31 a of the screw head 31 is disposed on the screw foot 32 side of the screw head 31 and has a diameter orthogonal to the longitudinal direction of the screw foot 32. It has a flange shape with a larger diameter than the part.

  The material 2 to be fastened, which is a thin metal such as steel, has a screw hole 21. The fastening material 1 is a thin metal such as a steel material, and in this specification, for convenience of explanation, one side, that is, the upper side surface of the fastening material 1 in FIG. Let it be back side Bb. The fastening material 1 has a corrugated burring 11 in which a part of the fastening material 1 is squeezed from the front side Ba to the back side Bb of the fastening material 1 to a burring height h by burring.

  Here, the fastening material 1 is used by plating a sheet-metal electrogalvanized steel plate (JIS symbol SECC-SD) and a cold rolled steel plate (JIS symbol SPCC) which is a general rolled steel plate. Alternatively, a high-tensile steel plate (JIS G3134, JIS3135 SPFH, SPFC, HTSS JFE-CA material, etc.) called a high-tensile material is also used. The plate thickness (t) is 0.4 mm as an example, but the range during implementation is about 0.3 mm or more and less than 0.8 mm in the case of an M3 screw (metric coarse screw size).

  The material used as a general-purpose material in the market is at the stage of 0.1 mm in SPCC, but it is a general commercial product of electrogalvanized steel sheet, and the thickness (t) is 0. 6mm above is 0.8mm. On the other hand, it can be similarly applied to other materials such as high formability stainless steel, brass and aluminum.

  When the plate thickness (t) is 0.8 mm, female threads can be formed by M3 tapping (JIS / ISO metric coarse thread) by ordinary burring. Therefore, when the M3 screw is applied substantially, the thickness (t) is in the range of 0.3 mm to 0.6 mm.

  However, although the details will be described later, the corrugated burring 11 of the present invention is a means for achieving the screw fastening strength in the thin sheet metal, and is not limited to M3, such as a metric fine screw or M1. It is possible to apply from precision small screws to large screws such as M4 and M5.

  In the present embodiment, the fastening material 1 having a thickness of 0.4 mm is provided with a corrugated burring 11 having a size for M3, and a corrugated shape having a screw hole 21 formed in the center portion of the material to be fastened 2. It arrange | positions so that it may correspond with the burring 11, and it fastens using the screw | thread 3. FIG. Screw 3 is a metric coarse tapping screw with a hexagonal cross hole head, and uses M3 RS tight (trade name) manufactured by Nitto Seiko Co., Ltd.

(Fastening structure)
The corrugated burring 11 of the fastening material 1 will be described in more detail.

  As shown in FIGS. 3 (a) and 4 (b), a corrugated burring 11 is provided on the back side Bb of the fastening material 1 at the center of the fastening material flat portion 1a. The central portion of the corrugated burring 11 is a female screw hole 12. The corrugated burring 11 is formed in a screw insertion direction at a height h from the fastening member flat portion 1a, in a substantially cylindrical shape longitudinal direction and radially outward of the female screw hole 12, and the inner peripheral surface 11c of the female screw hole 12. It is formed in a substantially cylindrical shape so as to surround the outer periphery of the screw and extending in the screw insertion direction. In the extended corrugated burring 11, valley folds 11 a and mountain folds 11 b are alternately and continuously repeated along the periphery of the screw foot portion 32 of the screw 3. The valley portion 11a ′ of the valley fold 11a formed in the screw insertion direction and the inner peripheral portion (that is, the screw hole 11c) of the mountain portion 11b ′ of the mountain fold 11b are engaged with the screw portion 32a of the screw 3. The distance from the trough portion 11a ′ to the crest portion 11b ′ of the corrugated burring 11, that is, the thickness (h11) of the engaging portion with the increased screw 3 in the screw hole burring portion (FIG. 3C) is 0. .6 to 1.2 mm.

  When the screw 3 is fastened, a flange-shaped dish-shaped screw brim portion 34 is formed on the contact side of the screw head 31 with the material 2 to be fastened, and the brim contact portion that is the outermost diameter contact surface The material to be fastened 2 is contacted by 2a. The material 2 to be fastened is fastened to the fastening material flat portion 1a by the screws 3. Therefore, since it is farther than the normal screw by the protruding portion of the screw flange portion 34, it has the characteristics that it is difficult to loosen and the loosening torque is also increased.

  By sequentially rotating and fastening the self-tapping portion of the screw foot 32 of the screw 3 as a tapping screw to the corrugated burring 11, a female screw is formed in the screw hole inner diameter portion 11c of the corrugated burring 11, and at the same time, the screw 3 The conclusion is completed by tightening.

(Structure of fastening part of fastening material)
Next, the fastening material 1 subjected to the corrugated burring process will be further described with reference to FIGS.

  5 and 6, a corrugated burring 11 having a substantially cylindrical shape is provided around a screw hole 12 at the center portion formed to protrude from the front side Ba to the back side Bb of the fastening material 1. The screw hole inner diameter portion 11c has a prepared hole diameter d11 so that a female screw can be formed. The pilot hole diameter d11 is the same as or substantially the same as the screw thread portion 32 of the screw 3. The corrugated burring 11 has a concavo-convex shape that is radially divided into 10 equal parts, and the ridges 11b and the valleys 11a are alternately and continuously repeated to increase the thickness (thickness) ( h11) is folded.

  In this embodiment, the plate thickness (t) of the fastening material 1 is 0.4 mm, and the cylindrical inner diameter (d11) is 2.459 mm, which is the diameter of a pilot hole of a cutting tap or a rolling tap of a metric coarse screw M3, or The inner diameter of the self-tapping screw pilot hole is set to 2.78 mm. Further, the thickness increase plate thickness (h11) corresponding to half of the difference between the inner diameter (d11) and the outer shape of the corrugated burring 11 is set to 0.8 mm. This is the same as the plate thickness of 0.8 mm, which is the processing limit of normal M3 burring. Therefore, if 0.8 mm was achieved by increasing the wall thickness, the screw fastening strength was 70% of the screw breaking torque 2 N · m shown in FIG. 2, and a fastening force of 1.4 N · m could be obtained.

  Usually, the fastening force of a screw is generally about 70% of the breaking torque. In the case of burring processing using a metric coarse screw M3, when the plate thickness is 0.8 mm, the burring pilot hole diameter (d11) is 0.9 mm, so the burring height (h) is based on the reason for volume unchanged. Is 1.4 mm including the plate thickness (t) (FIG. 5C). In the case of M3, since the screw pitch is 0.5 mm, a screw thread amount of 2.5 threads can be secured.

  In the present embodiment, when the corrugated burring 11 is formed with a plate thickness of 0.4 mm and a burring pilot hole diameter (d11) of 0.8 mm, the burring height (h) including the plate thickness is set to 1.6 mm. I was able to. As a result, it was possible to secure a screw engagement amount of three M3 screws. In addition, since the lead of the screw becomes long, the torque applied at the time of screw fastening can be dispersed, the damage of the burring can be further reduced, and wear due to repeated screw fastening can be reduced.

  On the other hand, in the case of a burring configuration for obtaining an appropriate fastening force with an M3 meter coarse tapping screw to a thin plate material of a plate thickness (t) 0.4 mm of a fastening material 1 formed of a metal material such as an electrogalvanized steel plate Is formed with a female threaded hole 12 in a cylindrical inner surface 11c of a corrugated burring 11 on a fastening material 1 which is a thin plate material, by a screw 3 which is tapped or a tapping screw.

  In this embodiment, the plate thickness (t) of the thin plate material that is the fastening material 1 is 0.4 mm, and the thread pitch of the metric coarse screw is 0.5 mm, which is set within a range of about 20%. is there.

  Further, when the plate thickness (t) is 0.3 mm, the metric fine screw M1 screw pitch is 0.2 mm to M3 screw pitch 0.35 mm, and the metric coarse screw is applicable to the M1 screw pitch 0.25 mm to M3 pitch 0.45 mm. is there.

  Similarly, in the case of the metric coarse screw M4, since the screw pitch is 0.7 mm, the plate thickness (t) can be applied in the range of M2 screw pitch 0.4 mm to M6 screw pitch 1 mm. In this way, the present invention can be applied to a plate thickness that is defined as a screw pitch that is substantially equal to the difference between the thread peaks and valleys and is thinner than the thread height. Therefore, it is applied to a plate thickness in the range of about ± 40% of the pitch of the screw applied to the pitch.

(Production method)
Next, with reference to FIG. 7, FIG. 8, the detail of the press work process for forming the waveform burring 11 is demonstrated. As shown in FIGS. 7 and 8, in this embodiment, the thin sheet metal that is the fastening material 1 is a strip-shaped plate 1A, and the fastening material flat portion 1a of the strip-shaped plate 1A sequentially performs the pressing process based on the transfer. A description will be given assuming that the burring 11 is formed using a progressive die.

  7 (a), 7 (b), 8 (a), 8 (b), and 8 (c) are diagrams showing processing steps for burring the fastening material of the fastening portion structure. (E) is sectional drawing which shows an example of the other shape of a burring. FIG. 7A is a perspective view seen from the front side Ba of the strip-shaped plate 1A, and FIG. 7B is a perspective view seen from the back side Bb. 8A is a side view, FIG. 8B is a plan view seen from the front side Ba, and FIG. 8C is a cross-sectional view.

  7 (a), 7 (b) and 8 (a), 8 (b), 8 (c), description will be made by arranging the pressing process so that the pressing process proceeds sequentially from the left side of the drawing to the right side.

  The first step is deep drawing for the fastening material plane 1a, and hemispherical drawing is performed to form a spherical stop 1b that protrudes from the front side Ba to the back side Bb of the fastening material plane 1a. The second step is drilling and radial bead forming, and a through hole 12 that is a screw hole is formed at the center of the spherical diaphragm 1b. Further, a diaphragm bead 11 ′ a having a concave and convex shape extending radially outward from the same center and extending radially is formed. The third step is a drawing-up thickening process, in which the spherical drawing portion 1b on the back side Bb is moved toward the center of the through hole 12 as indicated by an arrow C in FIG. Then, the radial drawn beads 11′a formed in the second step are formed to increase in thickness so as to form a cylindrical shape 11′b while forming peaks and valleys. A cylindrical corrugated diaphragm 11'b is formed while a radial portion of the radial diaphragm bead 11 'is folded to form a valley. The fourth step is a flattening process and a tapping process that is performed as necessary. By performing a pressing process to return the spherical diaphragm 1b to a flat surface so as to be the same surface as the original fastening material plane portion 1a, a wave shape is obtained. A screw hole 12 in which the burring 11 is formed is completed.

  In the spherical diaphragm 1b in the first step, the material that cannot be processed if the thin steel plate or the like of the fastening material 1 remains flat is changed to a spherical surface 1b that protrudes from the front side Ba to the back side Bb, thereby facilitating plastic deformation of the material. A drawn bead 11'a in the second step can be formed.

  Also, in the third waveform corrugation step, the portion of the spherical surface 1b that protrudes from the front side Ba to the back side Bb is tightened toward the center of the through hole 12 as shown by the arrow C in FIG. However, in practice, it is difficult to obtain a predetermined diameter in one process, so it is preferable to increase the number of processes.

  However, if the number of processes is increased, the number of molds increases, so that the corrugated height h11 of the corrugated burring 11, that is, the thickness of the corrugated burring, should be kept to the minimum range that can ensure the necessary thickness increase. .

  The bead uneven shape is not limited to a U-shaped cross-sectional shape as shown in FIG. 7C, but is a semicircular U-shaped shape (FIG. 7D) or a V-groove shape ( The process shown in FIG. 7 (e) is within a range where application settings can be freely made. In particular, when the bending process is severe in the drawing process or when the drawing process is severe, it is possible to prevent material bending cracking by distributing the stress in a U shape.

  In the fourth step, if the corrugation of the valley is left in the screw hole 12 with the inner diameter, the amount of engagement of the screw is substantially reduced, so that the breaking torque of the screw thread is reduced. Therefore, it is preferable that the screw hole 12 is a circle having as little as possible unevenness. For this purpose, a core shaft set to a desired pilot hole diameter (d11) by a mold is placed on the inner diameter side and finished with a press so as to be tightened from the outside. It is preferable to press. Alternatively, in order to increase the roundness and cylindricity of the inner diameter part for the screw pilot hole, the inner diameter is slightly reduced in the press work, and finish processing such as broaching or shaving by press working is performed. good.

  Finally, whether to form a screw thread in the screw hole 12 by a rolling tap or to use a tapping screw is determined depending on the application. In particular, when fastening screws on printed circuit boards that require electrical continuity, tapping can be performed using a rolling tap to ensure reliable torque management, thereby ensuring the contact pressure for electrical contact. Is possible.

  In addition, it is preferable to consider washing and oil with respect to chips and oil after pressing so that cutting powder generated in the case of self-tapping with a tapping screw or the like does not fall on the conductive portion.

  As described above, it is possible to provide a burring formed in a corrugated shape in which the cylindrical portion is thickened by the corrugated diaphragm 11 which is an uneven folding shape that substantially divides the circumference in the longitudinal direction of the cylindrical portion at the time of corrugated burring. .

Example 2
Next, Embodiment 2 of the present invention will be described with reference to FIGS. In the first embodiment, the corrugated burring 11 is formed around the screw hole 12 on the back side Bb of the fastening material 1. In this embodiment, a substantially rectangular radial bead 4 is further disposed around the corrugated burring 11. It differs from the first embodiment in that it is provided.

  In the present embodiment, in addition to the corrugated burring 11 described in the first embodiment, the thin plate material that is the fastening material 1 is subjected to press working at the screw fastening portion to the thin plate material that is the fastening material formed of the metal material. The radial diaphragm bead 4 having a bead shape is formed so as to be alternately concave and convex in a circumferential shape on a concentric circle from the center of the female screw hole 12.

  9 (a), (b), (c) and FIGS. 10 (a), (b) show the fastening material 1 to which this embodiment is applied. A corrugated burring 11 is provided around the screw hole 12 in the center of the back side Bb of the fastening material flat surface portion 1a as in the first embodiment. A radial diaphragm bead 4 is arranged in the fastening material flat portion 1a so as to be substantially concentric with the center O11 of the corrugated burring 11 and radially from the center O11, and the circumference is equally divided into ten equal parts. The radial shape bead 4 is formed in a concave shape in the screw insertion direction. In this embodiment, the width is 4w = 0.5 mm, the depth is 4h = 0.4 mm, the length is 4L = 1.5 to 4 mm, and both ends are formed in an R shape and narrowed. Distance from screw hole 12 ΔL = 1 mm. By additionally providing the radial shape bead 4, the reinforcing material flat portion 1 a is reinforced so that the bending strength in the radial direction is increased. As a result, jack-up of the flat surface portion that occurs at the time of screw fastening as shown in the conventional example of FIGS. 1 and 2 is reduced.

  As shown in Example 1, the corrugated burring 11 has a screw fastening strength of plate thickness (t) of 0.4 mm, but the tubular thickness (h11) of the corrugated burring 11 is equivalent to 0.8 mm by the thickening process. As a result, the fastening strength is improved. However, the strength of the flat surface portion 1a of the fastening material corresponding to this is weak if the plate thickness (t) is 0.4 mm, so the radial aperture bead 4 is provided. As a result, the plate thickness is equivalent to 0.8 mm, so that the screws can be reinforced with a good balance.

  FIG. 11 is a view showing a state in which the fastening material 1 and the material to be fastened 2 to which the present embodiment is applied are fastened with screws 3, and FIG. 11A is a perspective view seen from the front side Ba, FIG. ) Is a perspective view seen from the back side Bb. FIG. 12 is a view showing a state of a fastening portion structure 90 in which the fastening material 1 and the fastened material 2 to which the present embodiment is applied are fastened with screws 3, FIG. 12 (a) is a side view, and FIG. ) Is a surface plan view, and FIG. 12C is a partial cross-sectional view.

  In particular, as shown in FIG. 12 (c), the diameter d of the flange contact portion 2a with the material to be fastened 2 of the circular screw flange portion 34, which is the tip of the dish-like slope extending outward from the screw neck 35 of the screw 3, Since the circumscribed circle which is the outer diameter D of the substantially rectangular radial aperture bead 4 is arranged to be large, the fastening material 1 is reinforced so as not to be deformed.

(Production method)
Next, with reference to FIG. 13, FIG. 14, the process of the waveform burring 11 in a present Example is demonstrated. Also in the present embodiment, in the same manner as the press working step shown in the first embodiment, in FIGS. 13A, 13B, and 14A and 14B, the left side to the right side of the drawing are used. It is assumed that the pressing process proceeds in the direction.

  A spherical diaphragm 1b that is convex from the front side Ba to the back side Bb of the fastening material flat surface portion 1a is formed by spherical drawing in the first step. In the second step, a corrugated burring squeezing bead 11 ′ for processing the corrugated burring 11 is formed by drilling and radial bead forming. In the third step, corrugated burring is formed by squeezing and thickening. In the fourth step, the corrugated burring 11 is processed in the same manner as in the first embodiment by a flattening process and a tap process performed as necessary.

  The present embodiment is characterized by bead processing in the fifth step to be further performed. That is, a radial diaphragm bead 4 that is concave in the screw insertion direction is added so as to be positioned around the corrugated burring 11.

  In this embodiment, the circumference is divided into ten parts, but the present invention is not limited to this, and the radial aperture bead 4 is divided into arbitrary parts such as three equal parts and four equal parts. It is also possible. Further, the radial aperture bead 4 is formed in a circular shape, but is not limited to a circular shape, and has an arbitrary polygonal shape such as a triangle or a quadrangle, or an arc in consideration of the surrounding shape and other component arrangements. Different shapes are possible. Due to the radial diaphragm bead 4, the strength of the fastening member 1 in the fastening part structure 90 is increased, and jackup deformation at the time of screw fastening is reduced.

Example 3
Next, Embodiment 3 of the present invention will be described with reference to FIGS.

  The difference from the second embodiment is that the unevenness of the radial aperture bead 41 and the unevenness of the corrugated burring 11 are radially continuous, and have a bead shape that is integrally matched so that the circumference is equally divided into the same number. A thin plate corrugated burring 11 is different from the first and second embodiments.

  15 to 18 are diagrams showing this embodiment. FIGS. 15A, 15B and 15C, and FIGS. 16A and 16B are views showing the fastening material 1 in the present embodiment. 15A is a side view, FIG. 15B is a plan view seen from the front side Ba, and FIG. 15C is a cross-sectional view. 16A is a perspective view seen from the front side Ba, and FIG. 16B is a perspective view seen from the back side Bb. Further, FIGS. 17 (a), (b), (c) and FIGS. 18 (a), (b) are diagrams showing the pressing process of the burring 11 of the fastening material 1 of the present embodiment. 17 (a), (b), (c), and FIGS. 18 (a), (b), as in the first and second embodiments, the pressing process proceeds sequentially from the left side to the right side of the drawing. It is arranged. 17A is a side view, FIG. 17B is a plan view seen from the front side Ba, and FIG. 17C is a cross-sectional view. 18A is a perspective view seen from the front side Ba, and FIG. 18B is a perspective view seen from the back side Bb.

  In this embodiment, as shown in FIGS. 15 and 16, first, the thickened corrugated burring 11 shown in the embodiment 1 is provided on the thin plate material of the fastening material 1 formed of a metal material. A radial aperture bead 41 which is a radial bead is provided around the corrugated burring 11 as in the second embodiment.

  As shown in FIGS. 15 and 16, the threaded hole burring portion of the fastening material 1 is formed by alternately and continuously folding the corrugated crest portions 11 b and the trough portions 11 a obtained by dividing the circumference of the corrugated burring 11 into 10 parts. It is a state that has been. This corrugated burring can be processed in the same manner as in the second embodiment. In other words, the aperture beads 11 'shown in FIGS. 17 and 18 are gathered and formed, but the aperture beads 11' are lengthened so that the corrugated burring 11 is also formed outside. The remaining radial aperture bead 41 is molded. That is, the aperture bead 11 'and the radial aperture bead 41 are formed by the same processing in the pressing process. By providing such a continuous bead shape, the strength of the burring root is further increased. It aims at preventing the deformation | transformation of the burring base vicinity which is the characteristic of the jackup deformation | transformation by the screw fastening force shown in FIG. 1, FIG. According to the present embodiment, the fastening material flat portion 1a at the base of the burring is the reinforcement in the circumferential direction and the double reinforcement of the radial bead, and the thin plate portion is hardly deformed even with a fastening force of a prescribed strong torque, which is the most effective. It has become possible to provide a burring for a thin plate having a shape. The pressing process shown in FIGS. 17 to 18 is the same as that of the second embodiment, but the shape of the radial aperture bead 41 extending from the corrugated burring 11 is different. That is, since the radial aperture bead 41 is formed continuously with the corrugated burring 11, the respective irregularities are matched and connected.

  Briefly, the first step is deep drawing for the fastening material flat surface portion 1a, and hemispherical drawing processing that protrudes from the front side Ba to the back side Bb of the fastening material flat surface portion 1a is performed. A diaphragm 1b is formed. The second step is drilling and radial bead forming, and a through hole 12 that is a screw hole is formed at the center of the spherical diaphragm 1b. Further, a diaphragm bead 11'a having a diaphragm irregularity extending radially from the same center is formed. At this time, the formed bead 11'a is 11'a longer than those of the first and second embodiments. The third step is to increase the thickness of the squeeze, and the radial squeeze bead 11'a formed in the second step so that the spherical squeezed portion 1b is moved from the back side to the central portion forms a cylindrical valley. Increase the thickness to 11'b. At this time, the entire aperture bead 11 ′ a does not form the cylindrical shape 11 ′ b, and a portion of the aperture bead 11 ′ a is formed so as to remain around the aperture bead. In the fourth step, the flattening process and the tapping process are performed, and the spherical diaphragm 1b is pressed back to the same flat surface as the original fastening material plane portion 1a. A radial aperture bead 41 is formed.

Example 4
Next, Embodiment 4 of the present invention will be described with reference to FIGS.

  In this embodiment, the difference from Embodiments 2 and 3 is that the radial diaphragm bead 4 extending with the corrugated burring 11 as a concentric shape has a radially outer side when the fastening material flat surface portion 1a of the fastening material 1 is located. It has just been made into a fan shape that spreads out.

  19 (a), (b), (c), and FIGS. 20 (a), (b), the plate material of the material to be fastened 2 is fastened with screws 3 by the fastening material 1 to which this embodiment is applied. It is a figure which shows the fastening part structure 90, Fig.19 (a) is a side view, FIG.19 (b) is the top view seen from front side Ba, FIG.19 (c) is a partial cross section figure. 20A is a perspective view seen from the front side Ba, and FIG. 20B is a perspective view seen from the back side Bb. FIGS. 21 (a), (b), (c), and FIGS. 22 (a), (b) are diagrams showing the fastening material 1 of this example, and FIG. 21 (a) is a side view. FIG. 21B is a plan view seen from the front side Ba, and FIG. 21C is a side view. FIG. 22A is a perspective view seen from the front side Ba, and FIG. 22B is a perspective view seen from the back side Bb with the screw 3 fastened.

  As the radial shaped bead 4 moves away from the corrugated burring 11, the brim contact portion 2a whose strength is reduced by screw fastening is reinforced, and the thin plate fastening material 1 is reinforced to be deformed by the screw fastening force. It was made like this. At the same time, it is possible to obtain an effect of extruding with a fan-shaped portion so that the material is gathered in the central portion at the time of the spherical drawing in the first step in the pressing step, so that the thickness of the central portion of the fastening material 1 is suppressed from being reduced. The effect to do was obtained.

DESCRIPTION OF SYMBOLS 1 Fastening material 1a Fastening material plane part 2 Fastened material 3 Screw 4 Radial form diaphragm bead 11 Corrugated burring 11a Valley part 11b Mountain part 12 Female screw hole 32 Male thread part 41 Radial form diaphragm bead

Claims (14)

A screw having a screw head and a screw part;
A fastening material fastened by the screw;
Fastened material sandwiched between the screw and the fastening material and fastened to the fastening material;
In the fastening part structure, the screw hole of the fastening material into which the screw is screwed is formed by a substantially cylindrical burring part protruding in the burring process screw insertion direction,
The substantially cylindrical burring portion is a wave-shaped burring in which the burring-processed fastening material is folded in the circumferential direction and extends along the longitudinal direction of the cylindrical shape. . The fastening material has a bead formed radially outward from the outer diameter of the corrugated burring and extending radially outward from the center of the screw hole,
The fastening part structure according to claim 1, wherein the bead extends radially outward from the diameter of the screw head of the screw and is concave in the screw insertion direction. .   The fastening part structure according to claim 2, wherein the bead has a concavo-convex shape that coincides with a concavo-convex shape of the corrugated burring in a radial direction.   The fastening part structure according to claim 2 or 3, wherein the bead has a substantially rectangular shape extending radially outward from an outer periphery of the corrugated burring.   The fastening part structure according to claim 2, wherein the bead is formed in a substantially fan shape radially outward.   The said bead is arrange | positioned in the outer periphery of the said waveform burring, circular shape, or another different shape, The fastening part structure of any one of Claims 2-5 characterized by the above-mentioned.   The fastening part structure according to any one of claims 1 to 6, wherein the fastening material is made of a thin metal plate. A screw having a screw head and a screw part;
A fastening material fastened by the screw;
Fastened material sandwiched between the screw and the fastening material and fastened to the fastening material;
The screw hole of the fastening material into which the screw is screwed is processed in the screw hole burring portion in the fastening portion structure formed by a substantially cylindrical burring portion protruding in the burring-processed screw insertion direction. A method,
For the thin plate material constituting the fastening material, hemispherical drawing is performed, then drilling, radial bead forming processing is performed, then squeezing and thickening processing is performed, and then planarization processing is performed. A method of processing a screw hole burring portion having a fastening portion structure, wherein the corrugated burring is formed.   After processing the corrugated burring or simultaneously with the corrugated burring, a bead is formed so as to extend radially outward from the diameter of the screw head of the screw and to have a concave shape in the screw insertion direction. The processing method of the screw hole burring part of the fastening part structure of Claim 8 characterized by the above-mentioned.   The method for processing a screw hole burring having a fastening portion structure according to claim 9, wherein the bead has a concavo-convex shape that coincides with a concavo-convex shape of the corrugated burring in a radial direction.   The method of processing a screw hole burring of a fastening portion structure according to claim 9 or 10, wherein the bead is a substantially rectangular shape extending radially outward from an outer periphery of the corrugated burring.   The said bead is formed in the substantially fan shape to radial direction outward, The processing method of the screw hole burring part of the fastening part structure of Claim 9 or 10 characterized by the above-mentioned.   The screw hole of the fastening part structure according to any one of claims 9 to 12, wherein the bead is arranged in a circular shape on the outer peripheral surface of the corrugated burring or in another different shape. Processing method for burring part.   The method for processing a screw hole burring portion of a fastening portion structure according to any one of claims 8 to 14, wherein the fastening material is formed of a thin metal plate.

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